Rowing a SIB is hard work compared to a hard boat. If you row a wooden rowing boat, you give a good pull on the oars and it glides for a bit before the next oar stroke. Because SIBs are generally light, quite dumpy in shape, and they ride high int he water, they are very sensitive to the wind and tend not to glide between strokes. The best way to row a SIB is lots of short oar strokes rather than a few long ones. They are not really rowing boats.
That said, a few years ago I rowed my SIB across Loch Long to a dive site - but mainly to say I'd done it.
There are lots of cheap SIB hulls around. Unless you are keen to buy new,bide your time.